Two years ago this month, an oil pipeline burst in Michigan, contaminating 38 miles of the Kalamazoo River. It didn't get much national notice because everyone was focused on the massive BP oil spill in the Gulf of Mexico.

But the mess created by that Michigan spill was so great that it's become the costliest onshore spill in history — with a price tag of more than $800 million. On Tuesday, the National Transportation Safety Board blamed the spill on the failure of the pipeline operator, Enbridge Inc., to follow its own safety rules.

The NTSB said the federal government is culpable, too, because its Pipeline and Hazardous Materials Safety Administration does not have the staff or regulatory muscle to safeguard the public.

"Delegating too much authority to the regulated to assess their own system risks and correct them is tantamount to the fox guarding the henhouse," said Deborah Hersman, NTSB chairman.

Enbridge said it was trying to learn from the safety board to prevent future spills.

Cleanup work continues on the Kalamzoo River almost a year after the oil spill.

"We believe that the experienced personnel involved in the decisions made at the time of the release were trying to do the right thing. As with most such incidents, a series of unfortunate events and circumstances resulted in an outcome no one wanted," Patrick Daniel, Enbridge's CEO, said in a statement.

But the NTSB said if Enbridge had heeded the agency's previous recommendations and kept its 40-year-old pipeline in better repair, it could have avoided the accident altogether or at least minimized the damage it caused.

The Spill

On the evening of July 25, 2010, alarms indicating a leak starting going off in Enbridge's control room as soon as the pipeline burst open.

But three shifts of pipeline operators misinterpreted those signals.

At the scene of the gusher, people started calling 911 to report petroleum smells, but local emergency responders didn't know about the pipeline so they didn't think to alert Enbridge about the spill.

"It wasn't until late Monday morning, 17 hours and 19 minutes after the rupture, that a worker from a local gas utility found the spill and notified the Enbridge control center," Hersman said.

Only then did the company cut off the flow of the pipeline and send people to investigate.

By then, more than 800,000 gallons of crude oil had gushed into nearby wetlands and a creek.

The Aftermath

Even after Enbridge learned of the spill, it did such a bad job of trying to contain it that the heavy tar sands oil the pipeline carried spread through 38 miles of the Kalamazoo River.

"When we were examining Enbridge's poor handling to the response to this rupture, you can't help but think about the Keystone Cops," Hersman said at the NTSB meeting. "Why didn't they recognize what was happening? And what took so long?"

NTSB investigators determined that the 6-foot gash in the pipe was caused by a flaw in the outside lining that allowed the pipe to crack and corrode.

In 2005, Enbridge actually had learned that this section of the pipe was cracked and corroding from a report on the condition of the pipeline from an Enbridge contractor.

"Yet for five years they did nothing to address the corrosion or the cracking at the rupture site, and the problem festered." Hersman said.

That same 2005 report pointed to 15,000 defects in the pipeline, and Enbridge decided not to dig up this area to inspect it.

"A culture of deviance in the Enbridge control center was displayed in this accident," said Barry Strauch, one of the NTSB investigators, echoing a phrase used about NASA's risky decision that led to the Challenger disaster in 1986.

Enbridge did report these defects to the agency charged with pipeline safety, the Pipeline and Hazardous Materials Safety Administration.

But according to NTSB investigators, that agency is poorly staffed and its regulations are weak, so it was unable to adequately oversee companies' pipeline safety plans.

What's Next?

Hersman says the pipeline safety agency should have the power to make sure companies aggressively inspect their pipelines and replace them before they get so decrepit that they burst and endanger communities.

The NTSB made 19 recommendations about how the company, industry and government regulators should improve pipeline safety.

Hersman says that Enbridge and other pipeline companies and regulators have failed to listen to the NTSB recommendations in the past, and she warns that more spills will be on the way unless the whole pipeline industry starts listening and makes safety as big a goal as profits.

Transcript

ROBERT SIEGEL, HOST:

Two years ago this month, an oil pipeline burst in Michigan. It didn't get much notice because everyone was focused on the massive BP oil spill in the Gulf of Mexico. But like the BP spill, that Michigan spill was also one of America's costliest. So far, more than $800 million, and it's still being cleaned up. Today, the National Transportation Safety Board says the spill could and should have been avoided. Here's NPR's Elizabeth Shogren.

ELIZABETH SHOGREN, BYLINE: On the evening of July 25, 2010, alarms started going off in a control room as soon as the pipeline burst open. But three shifts of pipeline operators misinterpreted those signals. Deborah Hersman chairs the NTSB, which was charged with figuring out what caused the catastrophic spill.

DEBORAH HERSMAN: It wasn't until late Monday morning, 17 hours and 19 minutes after the rupture, that a worker from a local gas utility found the spill and notified the Enbridge control center.

SHOGREN: Only then did Enbridge, the Canadian company that owns the pipeline, turn off the flow of the pipeline and sent people to investigate. By then, more than 800,000 gallons of crude oil had gushed into nearby wetlands and a creek in Western Michigan.

NTSB Chair Hersman says even when Enbridge detected the spill, the company did such a bad job of trying to contain it that the heavy tar sands oil the pipeline carried spread through 38 miles of the Kalamazoo River.

HERSMAN: When we were examining Enbridge's poor handling their response to this rupture, you can't help but think about the Keystone Kops. Why didn't they recognize what was happening, and what took so long?

SHOGREN: NTSB investigators determined that the six-foot gash in the pipe was caused by a flaw in the outside lining which allowed the pipe to crack and corrode. Now, in 2005, Enbridge actually had learned that this section of pipe was cracked and corroding.

HERSMAN: Yet for five years, they did nothing to address the corrosion or the cracking at the rupture site. And the problem festered.

SHOGREN: That same 2005 internal report pointed to 15,000 defects in the 40-year-old pipeline. And Enbridge decided not to dig up this area to inspect it. Enbridge did report those defects to the agency charged with pipeline safety, the Pipeline and Hazardous Safety Materials Safety Administration. But according to investigators, that agency is poorly staffed and its regulations are weak.

Hersman says the pipeline safety agency should have the power to make sure companies aggressively inspect their pipelines and replace them before they get so decrepit.

HERSMAN: Delegating too much authority to the regulated to assess their own system risks and correct them is tantamount to the fox guarding the hen house.

SHOGREN: After the NTSB meeting today, Enbridge officials said they were not prepared to give an interview. But the company said in a press release that it has already improved its practices, and it is now reviewing the NTSB report to see if it needs to make more changes.

Hersman says that Enbridge and other pipeline companies and regulators have failed to listen to the NTSB recommendations in the past. And she fears that more spills will be on the way, unless the whole pipeline industry starts listening and make safety as big a goal as profits. Elizabeth Shogren, NPR News, Washington. Transcript provided by NPR, Copyright NPR.